In a surgical robot system, a forceps system comprising a forceps manipulator is practically used. As shown in Hagn, U., et al., DLR MiroSurge: a versatile system for research in endoscopic telesurgery, International Journal of Computer Assisted Radiology and Surgery, Vol. 5, p. 183-193 (2010), 10.1007/s11548-009-0372-4, for example, such a forceps manipulator has an arm with two degrees of freedom inside a human body (three degrees of freedom including a grip), and an arm with four degrees of freedom outside the human body. Such an arrangement is due to a restriction that implementing multiple degrees of freedom is difficult at a tip portion of a thin forceps provided in a forceps manipulator.
In addition, for a forceps manipulator, as also shown in K. Xu, R. Goldman, J. Ding, P. Allen, D. Fowler, and N. Simaan, “System design of an insertable robotic effector platform for single port access (spa) surgery”, IEEE/RSJ International Conference on Intelligent Robots and Systems, pp. 5546-5552, 2009, for example, a flexible forceps manipulator is proposed that can bend with four degrees of freedom within the abdominal cavity of a human body. A bending portion of the forceps manipulator is divided into two segments. Each segment is bendable with two degrees of freedom. A bendable elastic body is formed by connecting a plurality of metal plates with a superelastic alloy tube running through the respective centers of the plurality of the metal plates. Further, its bendability is achieved by running through a driving tube or a wire made of superelastic alloy on peripheral portions of the metal plates. An upstream joint constituting one segment is driven by four superelastic alloy tubes, while a downstream joint constituting the other segment is driven by four superelastic alloy wires. The superelastic alloy wires for driving the downstream joint respectively run through inside the superelastic alloy tubes for driving the upstream joint. This gives advantageous effects of allowing for reducing an arrangement space for driving-force transmission components of the forceps manipulator, as well as simplifying kinematic calculations of the forceps manipulator.
Furthermore, for a forceps manipulator, as shown in Haraguchi, D., et al., “Development of Pneumatically-Driven Forceps Manipulator Using Push-Pull Mechanism Made of Superelastic Alloy Wire”, for example, a forceps manipulator for laparoscopic surgery is proposed that has a simple flexible bending mechanism suitable for reduction in size. A joint structure of the mechanism is made from only a machined spring molded in one piece. A superelastic alloy wire running through inside this joint structure is operated in a push-pull motion by a pneumatic cylinder, and this allows for bending motions with higher rigidity than an antagonistic driving that utilizes a conventional wire tension. This allows such a joint structure to bend in directions of two degrees of freedom.
Then, as shown in Daisuke Haraguchi, Kotaro Tadano, Kenji Kawashima, A Prototype of Pneumatically-Driven Forceps Manipulator with Force Sensing Capability Using a Simple Flexible Joint, 2011 IEEE/RSJ International Conference on Intelligent Robots and Systems, pp. 931-936, a simple theoretical model is proposed for estimating an external force in the forceps manipulator, which model approximates a flexible joint in the forceps manipulator by a rigid linkage mechanism with two degrees of freedom.